The advantage is that it provides you with straightforward access from ground level, where you can easily do an inspection by lifting the lid and pulling up the WaBack module. It is supplied complete with an inspection chamber and non-return valve in one, and it has an open flow under normal conditions and closes as soon as there is any backflow. WaBack Access withstands 5 metres of back pressure, is reliable and has been used for more than 20 years.